Questions regarding password-based authentication and password management

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5
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4answers
817 views

How do I put comments in my /etc/shadow file?

I am running through some system upgrades and my package manager is showing changes between the upstream /etc/shadow and mine. I would like to put some comments in the file for next time this ...
5
votes
2answers
258 views

How is the su command masking/protecting my password from being displayed on screen? [duplicate]

Apologies if this is an abstract question - I'll try to be as specific as possible. When I'm at the bash shell and switch to a different account via su - foo, I'm prompted for a password. The ...
5
votes
3answers
2k views

Remote shell script Enter passphrase for

How can I run a script to log into a remote server and execute a remote ssh command without entering in my passphrase? For example: When I log onto a remote server and execute the git pull command I ...
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2answers
2k views

How to set default password algorithm to sha512 on Linux?

on AIX, it would be a simple: chsec -f /etc/security/login.cfg -s usw -a pwd_algorithm=ssha512 Question: But how can we set the default password algorithm to sha512? UPDATE: I think pwd_algorithm ...
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2answers
2k views

How to disable the try again password in ssh command

I want the ssh command to only allow one chance in typing the password, if the password was wrong at the first time the ssh will return Permission denied (publickey......). Is there a flag that ...
5
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1answer
2k views

Not able to set password in ArchLinux

I logged in as root and created a new account: # useradd -d /home/onie -m onie # su onie Now I try to set the password for onie myself using the passwd command, but it's asking for my current ...
5
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1answer
1k views

What triggers this screen prompt “Screen used by <username> on host01.”?

Every now and then some key combination clears my working (Gnu) screen and brings up this message: Screen used by <username> on host01 Password: What key combination causes this and what does ...
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4answers
6k views

Force Firefox to remember passwords on particular sites

Usually, when I log into a website with username and password, Firefox asks whether it should remember the login details. When I click yes, next time I visit the website, the username and password ...
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2answers
2k views

How to check for empty passwords?

Looking at all the ssh-login attempts by script-kiddies I assume that there are messed up systems connected to the internet that have password-less accounts set up. But how to check a Linux/Unix ...
5
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2answers
495 views

Why is 8 numbers considered a “strong” password?

Just curious as to why 8 numbers are accepted as a password in linux (CentOS if it matters) and not 8 characters on a non-dictionary word. It's 10 vs 26 per digit after all. (52 counting CaSe ...
5
votes
1answer
264 views

Is it safe for my ssh user to be given passwordless sudo for `apt-get update` and `apt-get upgrade`?

I have an SSH standard user account on my personal server, and it has sudo access (via its password). I ssh in using a public key, so I don't have to type in the account password to log in. Is it ...
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2answers
5k views

Graphically ask for password in a bash script and retain default sudo timeout setting

The sudo -A (SUDO_ASKPASS) option apparently causes sudo to lose the timeout (e.g., timestamp_timeout) setting. I want to use the sudo -A option but I want to retain the default timeout (e.g., 15 ...
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2answers
2k views

Scripting htdigest -c /path/to/file/$user $user $password in Bash

I want to be able to script with a password in variable $password. htdigest -c /etc/apache2/pw/$user $user $password At the moment it asks me to manually enter a password; this is not going to be ...
5
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1answer
489 views

Automated ssh login with passphrase?

Logging onto a machine over ssh typically requires a password to be entered before access is granted. Alternatively, a key/certificate (without a passphrase) can be installed onto the remote machine ...
5
votes
2answers
5k views

Unable to pass the password to su in a script

I am writing a build script. This script has to copy a file in the end. This file will be placed in another users home directory and it is also necessary that the file belongs to this second user. My ...
5
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2answers
577 views

Is it possible to change passwords temporarily?

I have a Linux system with several users. I don't know their passwords, nor do I want to know them. I have to do a batch copy of some of their directories over SSH, with their account and password. ...
5
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2answers
3k views

Why does pam_mount ask for password?

I used the pam-auth-update tool in order to enable some pam configuration profiles: PAM configuration PAM profiles to enable: [*] encfs encrypted home directories [*] Unix ...
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3answers
1k views

securely automating a script which requires a key to do its task

I have a script that downloads bank transactions to store in a database. To get these transactions requires a password for each account. The database is encrypted and requires a key to access it. All ...
5
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1answer
4k views

Changing password in multiple boxes using script

I'm working in a environment which has around 400 AIX boxes. I don't have root access and I'm a normal user. The environment has no LDAP kind of centralized mechanism for authentication so the ...
5
votes
1answer
5k views

Preventing `passwd` for asking for the local password

I have setup the sever to only use LDAP for authentication by using authconfig-tui. Everything works well but, when I run passwd, I get two prompts for a password: [beamin@rhel6-test-server1 ~]$ ...
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4answers
2k views

automatic passwordless ssh at login/restart

I want to have passwordless ssh to persist even after after I restart or logoff and then login. Somehow I have to run ssh-agent and use command ssh-add at login. In a tutorial I read that I should add ...
5
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3answers
480 views

Usage of pinentry with keepass2 for gpg mail encryption

Debian Jessie, XFCE 4.10, KeePass2, IceDove (with Enigmail).. I'm using KeePass2 generated passwords for my gpg private key, to de/encrypt mails. Icedove is my client which uses the enigmail. As ...
5
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1answer
4k views

Samba passwords expiring in x days - how do we fix them to not expire

We use OpenLDAP and Samba v3. Recently some Samba-defined users (no accounts on the shared linux server) started being listed in logwatch as having their passwords come up to "will expire"...I ...
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2answers
2k views

Can KWallet manage my ssh passwords?

I need a way to store some SSH passwords. Note that these are login passwords which I need to pass to ssh; key authentication is unfortunately not an option. I'd like to be able to have KWallet fill ...
4
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3answers
881 views

Any disk encryption that locks itself for some time after a number of failed attempts?

Is there any way to have your disk/partition/file encrypted (in Linux or as a hardware encryption; no Windows here) in such way that it locks itself for say 10 minutes after say 3 failed unlock ...
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7answers
7k views

Hiding Password in Shell Scripts

How can I hide a password in shell scripts? There are a number of scripts that are accessing database. If we open the script others also aware the username and password. So if anyone knows how to hide ...
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5answers
527 views

Does ssh send the password over the network?

Basically the entire question is in the headline: Does ssh send the password over the network? Presuming of course that login via username and password is used. I'm asking because if ssh doesn't send ...
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3answers
5k views

SCP command with selected file and directories for download ask's for password for each new file or directory

On my Fedora 20 system I use scp a lot, and this is the second time I encounter this, when I run this command: scp -r -P PORT user@host:/home/user/something/{file1,folder1,folder2,folder3,folder4} ...
4
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4answers
13k views

What command should I run after making changes to /etc/passwd file

I have made some changes to /etc/passwd file ,now I wanted to see if the effect of changes taken place or not .What command should I run for that. For example after making change to /etc/ssh/...
4
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3answers
1k views

Securely feeding a program with a password

After understanding the problem with using a password in the command line, I need to find a way of feeding a program with a password without it being a problem (without the password being recorded ...
4
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3answers
302 views

Automatic login via ssh (no GUI environment installed / no ssh-agent available)?

I have three systems, and I want to have them doing backups between them periodically. The two of them, have Debian Wheezy installed and the other one has Ubuntu 12.04 installed. Only the Ubuntu has a ...
4
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2answers
13k views

How to remove root password on Debian?

I'm running Debian in a virtual machine and for convenience I would like to remove the password on root (since it doesn't really matter what happens to this box). Internet hasn't been too helpful on ...
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2answers
401 views

Trying to crack a weak password using John

I have a computer from the 1990s. It has an (extent) EFS file-system which cannot be wrote to in linux, so i cannot reset the password manually. So i have to crack my password. For this I am trying to ...
4
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2answers
3k views

/etc/shadow date of last password change—UTC or local time?

man 5 shadow gives the following description of the third field in each line: The date of the last password change, expressed as the number of days since Jan 1, 1970. The value 0 has a ...
4
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2answers
240 views

Why rejection of password is much slower than acceptance of it? [duplicate]

In both my Linux and OSX machines when I type in the password to login, a correct password is accepted immediately. However, if I type a wrong password, checking process takes much longer. How is ...
4
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4answers
420 views

Login into a GNU/Linux distribution is taking too long

So, When I try to login with my username and password (in tty), and insert a wrong password, I need to wait around 5 seconds for the system to tell me that the password is wrong. Why the validating ...
4
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3answers
502 views

Something like pwgen-win for linux?

Is there some kind of pwd generator for Linux that has a nice GUI and options like this one for Windows? I know that there is pwgen, but as far as I know it does not support mouse/keyboard entropy and ...
4
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2answers
3k views

Why should you NEVER edit the /etc/shadow file directly?

In another answer here on UNIX & Linux Stack Exchange Michael D Parker wrote, in response to someone saying that doing so was "safe", that:Usually you should NEVER edit the /etc/shadow file ...
4
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4answers
63k views

Kali Linux: On install, designated root password cannot login - incorrect password

I found an old laptop lying around and I figured I would install Kali Linux on it to learn more about penetration testing and to try to break into my servers for practice and learning more about ...
4
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2answers
271 views

Determining the Password Status of a User

I have a debian box that I connect to via SSH. I have removed the password from the users root, and my personal account using the instructions here, and set up a public/private key pair so I can log ...
4
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2answers
458 views

User created without a password behaves as if he had one

Inside one of my scripts, I created an user based on a directory arrangement on another machine. The thing is that this user, created without a password, behaves just as he had one : he has sudo ...
4
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1answer
21k views

How to set password for users in AIX using single line command?

Is there any way in which I can set the password for a newly created user account in AIX in a one line command? I don't want to give any prompt to the user. If there is a command, it should set the ...
4
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1answer
517 views

Encrypt word X to /etc/shadow encryption

I've changed my password to X and the shadow file has changed to: ahmad:$1$oYINSKjP$eCkCtJV/2dXerAD57WQPj/:15425:0:99999:7::: I see the encrypted X as $1$oYINSKjP$eCkCtJV/2dXerAD57WQPj/. How can I ...
4
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1answer
1k views

Does OpenBSD use bcrypt by default?

http://codahale.com/how-to-safely-store-a-password/ with what does OpenBSD store the password by default? They say bcrypt is way more secure then hashing. I googled' it and obsd supports bcrypt, but ...
4
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2answers
441 views

Password protecting a system file? (e.g. /etc/resolv.conf)

I am trying to parental control myself by restricting web access via OpenDNS. The OpenDNS account password will be handed to someone trustworthy. Now, I want to put some restriction on the /etc/resolv....
4
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1answer
22k views

How to create a user with given password on SuSE from command line?

I need to create bunch of new users with given password. What I want is a script that I would pass the user name of new user and it will create/add the user and set its password. (the password is the ...
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3answers
2k views

scp: localhost password not accepted

I'm attempting to copy a public key to a remote server. I'm logged in locally as [localname] and the key resides locally at ~/.ssh/. I'm also ssh'd into [remote.com] as [remotename], and attempting to ...
4
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1answer
2k views

Why 'mkpasswd -m sha-512' produce different result every time it is called?

I am using this function to create a password in the shadow file $ mkpasswd -m sha-512 password $6$o50n4EfNOBzfs$K5l5AcOI5e0I9n2df0LmR11OLSPKSVM6AGBOnWVfDDfMubb46MrAj0zehdLNEoYzD2fj5q4XUdDwexj/dWLHy/ ...
4
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2answers
11k views

Avoid “Authentication token manipulation error” on password change

I'm implementing a security policy that will force the users to introduce stricter passwords when they change their own: The /etc/pam.d/passwd configuration file is: #%PAM-1.0 auth include ...
4
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3answers
312 views

Randomise or shred memory of an application

Is it possible to randomise or shred memory of a particular application just after its life ends, or better, whenever it deallocates some memory? A command-line utility like this would be perfect: ...